Question

Difference between adc and dac

Answer 1

Answer:

Data converters provide a transition between the analog and digital signal realms. The two basic converter types, analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), share many common circuit elements and even come in similar multi-pin packages. Key performance parameters are identical between the two, including clock speed, sampling rates, and bandwidth, but they differ in many other ways. Ultimately, understanding how the different characteristics can be used to describe an ADC or a DAC will help speed the task of finding an optimum data converter for a particular application.

ADCs sample continuous analog signals over an input voltage range and convert them into digital representations (words) with resolution equal to the ADC’s number of bits. Sampling occurs at the ADC’s clock frequency. DACs convert digital input code into analog output signals, essentially providing the opposite function of an ADC. Both types rely heavily on the performance of a clock oscillator (or oscillators) to achieve the most precise and repeatable sampling process.

An ADC’s performance is often presented in terms of both time- and frequency-domain plots. Time-domain plots show the component’s voltage as a function of time, whereas frequency-domain plots show signal power as a function of frequency, or the spectral performance, of an ADC. Spectral performance includes a number of parameters useful for comparing the capabilities of different ADCs, including effective number of bits (ENOB), signal-to-noise ratio (SNR), signal-to-noise and distortion (SINAD), spurious-free dynamic range (SFDR), and total harmonic distortion (THD). Additional ADC parameters, such as bandwidth, clock speed, and current consumption, can aid the task of specifying a commercial ADC for a particular application.

Answer 2

Answer:An ADC’s performance is often presented in terms of both time- and frequency-domain plots. Time-domain plots show the component’s voltage as a function of time, whereas frequency-domain plots show signal power as a function of frequency, or the spectral performance, of an ADC. Spectral performance includes a number of parameters useful for comparing the capabilities of different ADCs, including effective number of bits (ENOB), signal-to-noise ratio (SNR), signal-to-noise and distortion (SINAD), spurious-free dynamic range (SFDR), and total harmonic distortion (THD). Additional ADC parameters, such as bandwidth, clock speed, and current consumption, can aid the task of specifying a commercial ADC for a particular application. DAC essentially does the opposite of an ADC, converting digital inputs to analog output signals. The analog signals are generated at the sampling frequency applied to the DAC clock. As with an ADC, the key spectral-performance parameters for a DAC include SNR and SFDR. DAC specifiers must also be concerned with a device’s adjacent-channel leakage ratio (ACLR) and third-order intermodulation (IMD3). Both are forms of distortion, yielding unwanted additional signals, with IMD3 related to third harmonics of the clock driving the DAC.

Explanation: